Welcome to the Jungle
by Blue-Five
Summary: Chicago Fire AU (alpha/omega) - Matthew Casey was an omega ready to prove himself. Of course, then he ran into Kelly Severide.
1. Chapter 1

**DISCLAIMER:** This is a work of fiction using characters from the Chicago Fire universe. I do not claim any ownership. This work is solely for entertainment purposes and is not considered film or tv canon (not by a long shot).

**A/N: ** I'm very new to this fandom but I love a/b/o stories and I'm in love with Casey/Severide. Hope you enjoy - comments appreciated.

* * *

><p>"Paramedic? But I applied for –" Matthew Casey began.<p>

The employment counselor smiled and Casey thought his lips fairly oozed with condescension. "I know what you applied for, kid. Look … no one is gonna put an omega on a truck. Period. It ain't gonna happen. But paramedics are right up your alley … you stay outta danger and you get to do what you were born to do – take care of others."

Casey clenched his jaw in a near-futile attempt to keep his temper. "But I've been training –"

The counselor sighed. "I know that too … you have to live in the real world, kid. Sure, there's lots of do-gooders out there getting laws passed giving you omegas all sorts of freedoms and such … but this is Chicago. And until the law says different, I can't place you in a testing class for being a fireman. I mean, how're you supposed to manage that? You'd be working with a buncha alphas day in and day out. Not to put too fine a point on it – you go into heat and you could shut the entire house down. And how would that look? People don't wanna read how some grandmother's house burned to the ground with her in it cuz the closest firehouse was too busy fuckin' their pet omega."

Matt blew out a frustrated breath. "They make suppressants –"

"Which can have some serious side-effects and possibly leave you sterile," the man countered. "You're young … why would you wanna take the chance that you might never have pups of your own when you meet your alpha?" The counselor smiled pityingly.

"I have to take them to have the paramedic position," Casey pointed out.

"Yep, and you'll be drug tested monthly to make sure you're on 'em. But no omega stays employed in a job like this more than a year anyway … probably not long enough to harm you," the man explained.

"Why not more than a year?" Matt asked.

"After a year, most omegas decide they can't go against nature. They start wantin' pups and home and all the stuff you omegas were created for – they find an alpha and they settle down."

"That won't be me," Casey insisted. "I want this to be my career … well, I _want_ to be a fireman, but if I can't have that then I'll take paramedic. And I won't be leaving in a year."

The counselor gave Matt a smug look. "Whatever you say, kid. You ain't the first omega to come through here with his or her head in the clouds. You won't be the last. You come see me when you need a referral for a teaching position or maybe when you want to be a nurse."

_You mean when hell freezes over_, Matt thought angrily.

He grabbed the paperwork and stalked out of the employment center. He didn't care what the hell society dictated for him. He'd find a way to work in a firehouse. Somehow.

* * *

><p>The world was changing and Kelly Severide wasn't completely in agreement with it but he tried to not be Neanderthal about it. Alphas filled a certain role in society – they were the protectors, the warriors, the ones that ran into danger. Betas could fill that role as well although few did. Omegas … Severide winced as he thought about the announcement made by Chief Boden this morning. Omegas were winning new rights every day it seemed but Kelly had always believed his world was sacrosanct. The only omegas that came into the station were mates or pups of the firefighters that worked there. Perhaps representatives from support groups. No omega had ever <em>worked<em> in the quarters of Engine Co. 51, Truck Co. 81, Rescue Squad Co. 3 and Ambulance 61. Hell, even Boden's assistant, Connie, was a beta – although it was widely rumored that was just a front and she was actually an alpha. And now they'd gone and slapped Leslie Shay, current lead on the ambulance, with an omega partner on the ambo.

"It's a disaster waitin' to happen," Hermann muttered. "Omegas have a place and this ain't it."

Shay gave a frustrated growl. She, like Connie, was a beta but she could go toe to toe with an alpha any day. Kelly knew that one for certain since she was his roommate and best friend.

"It's just so stupid! Gabby was ready to come onboard – she's one of the best!" Shay protested. "Now what am I supposed to do?"

"Make it work," came a low growling voice from the doorway.

Chief Wallace Boden was a legend in his own time. A scarred veteran of the department, Boden was an alpha's alpha. He didn't take shit from anyone and his house was loyal to him. He'd frowned over the admission of betas 'back in the day' but the world hadn't ended. He didn't necessarily like the omega being thrust upon them now, but he was going to do whatever was necessary to show his house as one that could adapt.

Of course, if the omega couldn't pass muster that was another matter entirely.

"Chief, what the hell are we supposed to do when he goes into heat? I mean, he'll be out of commission for at least a week every month!" Shay grumbled.

Boden sighed heavily. "We will provide a non-hostile environment at this house – that means regardless of designation or sex or any other category someone falls into, we will welcome them and give them _every_ opportunity to prove themselves. Do I make myself clear?"

Boden listened to the desultory responses in the affirmative and tried to ignore the looks that flew around the room. He did not envy the newcomer.

* * *

><p>Casey walked into the fire station and had to struggle not to gape like a tourist. Of course he'd been in fire stations before but never like this – never as someone who was going to be working side by side with the alphas that actually went out on calls. He toned down the smile threatening to break his face in two and approached the serious faced young woman currently coming out of the back of the ambulance. She took one look at him and rolled her eyes.<p>

"Oh good. You're here."

Casey ignored the sarcasm and stuck his hand out. "Matthew Casey. I assume you're P.I.C. Leslie Shay?"

Shay ignored his hand and nodded. "That's right. Now, let me fill you in on something, _Paramedic_ Casey … I had to work damn hard for this spot and you being here fucked up what could have been an awesome partnership with one of the best paramedics in the city. Don't expect a cakewalk."

Casey lowered his hand and nodded. "Fair enough. I figured I wouldn't get the red carpet."

"Baby, you have no idea. But come on … I'll show you around," Shay offered curtly.

Closing the back bay doors, she marched around the ambulance and headed for the station proper. Casey jogged to catch up and as he rounded one of the trucks, he ran headlong into a broad chest.

"Whoa! Sorry!" Casey apologized as he danced back.

Looking at the man he'd run into, Matt felt lightheaded. He swallowed hard and prayed his fair skin wasn't coloring the way he feared it was. When the man smiled at him, Casey was pretty sure the entire house heard his heart pounding. Of course, Kelly Severide took that moment to speak.

"Hey, you must be the new omega riding with Shay," Kelly said sweetly.

Casey nodded, not trusting his voice. The man was very obviously an alpha. It wasn't like he'd never met an alpha before but one had never affected him so quickly. He smiled nervously back.

Kelly grinned and suddenly Matt was reminded more of a shark than a teddy bear. "Well, you be good and do what she says. And, omega? See that table over there?"

Casey nodded with a frown.

"That's the squad table … buncha rowdy alpha assholes of which I count myself Lieutenant. I'd steer clear … sweet little thing like you and all might distract them. Can't have that, can we?" Severide said with a smirk.

Casey swallowed again, but this time it was the bitter sting of bile rising in his throat. He'd been so attracted half a minute ago … now he relished the retreating backside, even if it was very nicely proportioned.

"So. Whenever you're done flirting with Lieutenant Severide …?"

Matt jumped at Shay's voice right next to him. He cleared his throat amidst laughter from the squad table. He closed his eyes and exhaled in frustration as the alpha called Severide called out, "Aww, he blushes so _pretty_, Shay!"

Leslie flipped Kelly off to more laughter and turned on her heel, calling over her shoulder. "Come on, omega … this is only the beginning."

Not for the first time, Matthew Casey wondered if this was also going to be his ending.


	2. Chapter 2

Casey sighed inwardly as he met the emotionless faces of the alphas in the firehouse. It had been too much to expect, really. He was an omega walking into alpha territory. Uninvited. Shay indicated him with a wave of her hand as she went to grab a cup of coffee.

"Guys, our omega has arrived … Matthew Casey meet the guys," Shay said.

"Hey …" Casey began, only to realize that the room had turned a collective shoulder to him. He had to swallow the lump in his throat. "Yeah. Alright then."

Looking at Shay, Casey asked. "So where can I stow my gear?"

"Ok, that's it," Hermann spoke up. He looked at Matt. "Look, I get you got put here and it's all real nice for you but I draw the line at sharin' the locker room with you."

Matt frowned. "You share it with Shay and any other female that works here."

"They ain't omegas," Hermann said firmly. "They ain't puttin' out seven kinds o' pheromones to get all over everything. I mean, how are we supposed to instill confidence in our public if we show up smellin' like omegas?"

"Is _that_ what that smell is?" Randy "Mouch" McHolland said brightly. "And here I thought you forgot where we keep the soap!"

Laughter floated through the room, but Casey didn't feel much like joining in. He shouldered his bag and Shay rolled her eyes.

"You can stow it in the ambulance," she said.

Matt shook his head. "Against regulations. It's fine. I'll manage."

"Look, Casey, we can make room –" Shay began.

"I said it's fine … so in light of my offensive odor, do you guys have a place for me to sleep?" Casey asked quietly.

The room fell silent and a snicker went up. "He got you there."

Matt looked over at the one alpha who really hadn't said anything since Shay's introduction. The man stood and Casey was forced to wonder what deity that he'd offended with his forward ways that he was being forced to try and be in control around alphas so … aesthetically pleasing?

Lt. Jeff Clarke walked over to Matt and extended his hand. The omega shook it firmly eliciting a chuckle from Clarke.

"Yeah, my sire said the same thing about a good handshake," Jeff said with a smile.

Casey grinned. "Well, you're the first alpha I've had a chance to try it out on so how would you rate it?"

Jeff's lips quirked. "Adequate. Come on, I'll show you the sleeping arrangements."

"Aww come on! How are we supposed to sleep?"

"Tell me you don't have that little self-control, Hermann," Ortiz teased. "Now you're makin' me nervous."

Casey looked at Shay who rolled her eyes and followed the pair up to the bunks. Clarke surveyed the bunks and nodded toward the far end. "Down there … Hermann sleeps on this side usually."

"I'll bunk next to him," came a softer voice from behind them. "His scent won't bug me."

Matt turned to see a handsome young beta wearing a candidate shirt. He took the proffered hand.

"Peter Mills," the young man said. "Candidate."

"Nice to meet you," Matt said, shaking his hand.

"Yep … and give the guys time. They'll come around," Peter promised.

Casey smiled but inwardly, he held little hope. He'd had to deal with it through his training to become a paramedic … through school before that … he was used to alphas trying to put him in his place or run him off. It was tiring and he'd hoped for more but things were looking up. The alarm went off and suddenly he was being thrust into the next phase of his new life. Racing to the ambulance, Matt hoped he could live up to his own dreams.

* * *

><p>Listening to Shay bark orders, Casey let himself slip sideways into an omega headspace. His instructors had at first berated him for doing it but as he continued in the class, they quickly found it gave him an advantage for being a paramedic that no other designation possessed.<p>

Allowing his brain to create the chemical cocktail that made him submit to alphas and even pushy betas, Matt could filter out every other distraction. He was aware of his surroundings in a crystalline relief – his brain told him he had to be in order to do what he was being told. Shay's commands slipped into his mind and Matt was performing them almost before he realized what she'd said.

The call – a flipped vehicle – had required him to start an IV while squeezing into the cab at an awkward angle. Shay performed CPR on the ejected passenger in a dim hope the man would survive. Once Casey had the line set, the crews freed the driver and Matt moved into the back with the patient. Now he had to show that he knew his training.

Matt took a deep breath and called out his actions as he did them. Shay drove and gave direction as she felt needed but to her not inconsiderable shock, she figured out that Casey knew his stuff. His secondary skillset came into play as well when the woman awoke in a panic – he spoke softly to her. She was a beta, but one skill all omegas possessed was the ability to calm. His voice range dropped and the woman's breathing and heart rate returned to a more stable level.

"Impressive," Shay announced as they walked back to the ambulance after passing their patient off to the hospital staff. "Just watch it or I'll fall asleep driving."

Casey chuckled. "I'll keep that in mind."

However, once back at the station, Casey was called into Boden's office. He stood before the alpha's desk, uncertain as to what he'd done wrong. Shay was beside him, equally confused.

"Eventful first call, Casey," Chief Boden rumbled.

Matt nodded. "Yes sir, but I think I learned –"

"Allow me to finish?"

Matt felt his face grow warm and he nodded.

"It was observed by one of the squad that your eyes were dilated and you seemed … distant in your responses to P.I.C. Shay," Boden said.

Casey's eyes widened and he nodded. "Correct, chief. It's a technique I taught myself in training class … I can slip partially into my omega brain and keep a clear head while I'm working. It lets me ignore any distractions like –"

"Like the fact that you were in a semi-crushed vehicle working on a critically injured woman, correct?" Chief Boden asked.

Shay frowned. "He did everything by the book, chief."

"So he did … but when you are in your "omega brain" as you call it … who's commands do you recognize? Just Shay's? Severide's? Any other alpha on site?"

Matt swallowed. His teacher had warned him that his method had some drawbacks. "I can differentiate between alphas, chief. It's not a –"

"It will become a problem when you are out on a call where there are multiple companies and you do not know every alpha or beta in the area. It will become a problem when you take a command from one alpha and ignore another because they weren't 'first'. It will become a problem when that second command is for you to get your ass out of harm's way and your brain won't let you respond to it … or worse yet, you do respond and it was the wrong command and someone dies because you had no independent control over your thoughts and couldn't make a decision," Boden growled. "We do not work in carefully controlled circumstances, Casey. Out here you have to know your job and _learn_ how to ignore distractions and filter out conflicting orders."

Casey blinked. He realized all too clearly now that his habit was more detriment than advantage. He also realized that his instructors had known this all along. He couldn't stop his shoulders from slumping.

"I see you suspect, as I do, that you have been set up to fail. You have been prepped to be a weak link in this house," Boden said quietly.

Shay studied Casey for a moment. His work had been quick and efficient during the call. His responses had been correct and concise … he'd even managed to calm the patient in the middle of a stressful situation no human was truly prepared for. She could see that he wasn't going to be one of those omegas who sought out challenges _just_ to ruffle feathers. He_ wanted_ this life … and he had worked hard to grasp even the small piece of it that he was being allowed. She could well-remember her own struggles being a beta and a woman. She wondered how Casey would react to Boden's statement and was pleased to see him square his shoulders.

"I don't intend on being a weak link, Chief. I've shown I can do the job and I know I can learn to work through the distractions," Matt announced, his eyes flashing.

Boden raised an eyebrow. He looked at Shay. "And do you think he is capable?"

Casey didn't look at Shay. He couldn't. If he did and he saw smug assurance, he would know she planned on using his newfound training deficit to get him kicked out of the house. Worse yet, if he saw pity, he would know he was never going to be treated as an equal and she would coddle him until he simply couldn't bear it any longer. So he just stared straight ahead and waited for his sentence.

"I guess we're gonna find out, chief. I'm sure the guys can set up some training scenarios that'll break him of the habit and see if he can hack it," Leslie said quietly.

Casey looked over in shock to find her smirking at him. It wasn't unkind … just promising God only knew what by way of training. Boden cast his gaze back on Casey.

"Do you want to attempt to prove yourself worthy of this house or shall I submit the paperwork for you to seek a position elsewhere – perhaps in an administrative position?"

"I can take whatever they can dish out, chief. I'll do right by this house," Matt promised.

"Well, then … I guess we'll see what we see."

Matt walked out to the kitchen with Shay. He winced when he smelled the overwhelming odor of garlic. Shay looked equally nauseated.

"I don't suppose you cook?" she asked.

Casey grinned. "I'm an omega … I've had cooking classes forced down my throat since I was old enough to turn on the gas by myself."

For a first proof, the rest of the house had to admit Casey's quick spaghetti beat anything they'd had in a while. He was swiftly designated the house chef for his shift. Unfortunately, Shay informed the group of Boden's concerns. Casey wondered who had informed Boden of his trick but there were too many suspects to make worrying about it worth his time. Judging from the mischievous gleams in every alpha's eyes, Matt suspected he was in for a shock with his 'retraining'. He was not wrong.


End file.
